1. Field of the Invention
The present invention relates generally to skiing simulation apparatus and, more particularly, to such apparatus combining ski training and exercise and providing lateral and vertical motion, variable stance, multiaxial foot rotation and voluntary weight transfer, all of which enable realistic simulation of a full range of downhill ski techniques and terrain conditions.
2. Description of the Prior Art:
The sport of alpine or downhill snow skiing is enjoyed by millions of Americans and millions more worldwide but is extremely demanding. Safe and effective skiing requires considerable strength, endurance, balance and coordination as well as substantial technical skill. These challenges are met by all skiers, from beginners to experts, who must constantly test their limits as they strive to improve their technique and to master more and more difficult terrain. These difficulties are further compounded by the stressful environmental conditions under which the sport is performed. In the mountains, skiers are exposed to varying combinations of altitude, cold, alternating with overheating due to bursts of strenuous activity, wind, bright sun and snowfall, all of which can impair mental and physical performance.
The seasonality of the sport makes the physical conditioning necessary for safe and successful skiing difficult to sustain in the off-season. Unlike racers, who ski year-round by travelling wherever the snow is located, most recreational skiers are unable to participate for more than a small portion of each year. They clearly need a more practical way to practice and stay in shape, in order to get the most out of their ski vacations and to avoid injury. In the past, off season training options have been limited primarily to weight training and nonspecific aerobic activities such as running and cycling. Recently, rollerblading has introduced a cross-training activity with greater similarity to downhill skiing, but with its own limitations, including the need for an empty paved incline and a relatively high risk of injury. Unfortunately, these alternative exercise regimens rarely, if ever, emulate the parameters of actual on-slope skiing. Due to undertraining, recreational skiers, even those in relatively good condition, typically must endure several days of soreness and stiffness (i.e. muscle injury) at the beginning of their vacations before they "get their ski legs" and perform comfortably. Thus, for many or most skiers, mastery and enjoyment of the sport are limited by inadequate conditioning and insufficient practice.
Many of these problems would be greatly diminished by the development of a realistic ski simulator. The advantage of a ski simulator is the potential for a safe, ski-specific exercise that can be enjoyed at home or at the gym, any time and in any weather. An optimal device would reproduce the feel of skiing by emulating the correct anatomic positioning and physiologic loading experienced during a variety of ski techniques under various terrain conditions. The exercise intensity also should be adjustable, allowing skiers at all levels to develop their strength, endurance, balance, coordination and skill. A realistic downhill ski trainer would be suitable for off-slope and off-season ski simulation, conditioning and even instruction.
The opportunity to work face-to-face with an athlete performing under relaxed, controlled indoor conditions would add a new dimension to ski instruction and coaching. Ski schools could benefit by supplementing their regular mountain programs with off-slope and off-season instruction. A realistic ski simulator could be used to teach essential ski fundamentals (i.e. stance, balance, pressure, edging, steering, weight transfer, hip angulation, vertical motion, upper body position and poling) as well as integrated technique. Individual or group indoor instruction outside normal lift operating hours or during harsh weather would be valuable for skiers seeking to speed their progress and/or minimize cold exposure. Currently, skiers in group lessons are often frustrated by the need to repeatedly stop moving in order to receive instruction on the mountain. Coupling of on-mountain lessons with morning or evening indoor demonstrations and supervised simulation would help optimize the pace of outdoor lessons and maximize ski mileage. Dry land classes would be particularly useful for assessing and enhancing the readiness of children and physically challenged skiers to face mountain conditions.
The technical skills of alpine skiing range from the beginner level (snowplow turn and wedge christie) to intermediate (stem christie and parallel turns) to advanced (short swing, step christie and mogul skiing). Reproduction of these techniques requires analysis of their underlying anatomic and physiologic elements. We can define a limited number of basic elements which can be integrated to produce the full spectrum of alpine skills. These include lateral (side-to-side) leg motion with a variable stance, vertical leg motion (flexion/extension), and voluntary weight transfer effected by edging and by a resistive pole plant. Two additional degrees of freedom experienced during free skiing include inward and outward toe rotation and ankle flexion/extension.
Prior art citations relate primarily to cross-country rather than downhill ski simulation. Specific references are U.S. patents to Engel et al.: U.S. Pat. No. 5,026,866 and Chi: U.S. Pat. No. 5,299,966. A limited number of downhill ski trainers also have been available. These devices, which have been discussed in the recent press, for example, in Consumer's Reports, September 1994, pages 582 et. seq. and in Skiing Magazine, October 1994, pages 66 et. seq. are very similar in their basic elements. The principal feature is a basic side-to-side motion, resembling the repeated turns of a skier making a controlled descent. Unfortunately, this lateral motion, while necessary, is not sufficient to reproduce the feel of downhill skiing. These designs are all limited by their fixed closed stance, absence of vertical motion, lack of voluntary weight transfer and lack of vigorous poling. On previous devices, the subject traverses a convex track rising 6 or 8 inches from base to peak but, due to the fixed closed stance, the feet are separated vertically by no more than a few inches at a time. Weight transfer is accomplished upon recoil of a big rubber band not controlled by the subject. The old models are also equipped with unattached poles, which are used for extra balance but do little to assist the weight transfer.
Because of these limitations, prior art devices cannot reproduce the full spectrum of modern ski techniques. In fact, they can only approximate a nonaggressive, closed track parallel turning technique used primarily by advanced intermediate skiers. They achieve nothing else above or below it in the hierarchy of alpine skills as taught, for example, in a document entitled "Strategies for Teaching, American Teaching System", and promoted by Professional Ski Instructors of America (Publishers Press, Salt Lake City, 1987). This isolated, invariant exercise thus fails to meet the needs of most skiers. The lateral motion is appropriate, but modern athletic skiing also requires dynamic vertical motion, meaning flexion and extension of the hips and knees. This has not been addressed in prior art citations.
The second problem is stance which ought not to be fixed and closed but variable, permitting each leg to execute its lateral motion independently. Beginners must maintain a wide stance to stay in balance. These skiers will not be comfortable on a trainer a requiring a fixed closed stance. In contrast, because of their excellent balance, expert skiers usually can handle a closed stance, but advanced techniques (e.g. step christie) also require a variable stance, without which better skiers would feel constrained. The third drawback of the prior art resides in the weight transfer, which should be under voluntary control of the subject, but instead depends upon passive recoil of an elastic band. Ordinarily, edge control creates a stable platform that permits precise weight changes and application of tremendous lateral carving forces. Without controlled weight transfer, the subject has to be quite tentative in executing the lateral motion, limiting the enjoyment and value of the workout. Finally, realistic poling would incorporate lateral arm resistance as an active part of weight transfer.